US3005790A - Road marking paint - Google Patents

Description

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3,005,790 ROAD MARKING PAINT James F. Wynn, Marietta, Ohio, and Harry N. Huntzicker,

Evanston, 11]., assignors to American-Marietta Comcorporation of Illinois Filed Aug. 28,1958, Ser. No. 757,823 9 Claims. (Cl. 260-22) The present invention relates to highway marking paint.

More particularly, it relates to highway marking paints adapted to be sprayed, rolled or brushed on highway surfaces subject to vehicular traflic to provide reflex lightreflective traflic markers, e.g., centerlines, having high night-time visibility to motorists. The highway marking paints of the invention are particularly characterized by enhanced durability under normal conditions of abrasive 'vehicular wear and are further characterized in that they can be produced at lower cost, loaded with reflex reflecting elements to a greater extent and with improved suspension characteristics and provide greater resistance to skid than conventional reflective highway marking paints.

To the present time, the production of commercially suitable reflex reflective traflic markers has always been considered to require as an essential feature thereof, the use of spheres or beads to provide the reflex reflective action. customarily, a paint composition was applied to the previously laid and partially dried paint. The reflective traffic markers so formed provided adequate initial reflexreflective qualities. However, the reflex reflective quality was short lived and not durable. Also, the two-stage application procedure was slow. and laborious and added to the cost of producing the traflic marker.

In the United States patent to Heltzer, No. 2,574,971, dated November 13, 1951, Highway Marking Paint Containing Glass Beads, the glass spheres or beads were incorporated in the paint and the paint and the glass spheres applied together in a single stage. The paint film above the beads of this composition is worn away to expose the tops of the beads and in this manner a reflex reflective surface is developed through wear. The durability of the reflex reflective action, although somewhat improved, does not provide the high standards. of night-time visibility for adequately long periods of time.

When'only a small proportion of the .top of a given bead is exposed, the reflex reflective action is poor- When a larger proportion of the bead is exposed, the bead becomes easily dislodged and the surrounding paint is subjected to heavy wear. Thus, the reflex reflective action is limited by these two factors. When the beads become sutficiently exposed to participate effectively in the reflex reflective action, they tend to become easily dislodged. The effectiveness and durability of the traflic marker is thus substantially impaired.

When the marking-paint is applied to the highway itself, the dislodged beads do more than reduce the reflective quality and durability of the marker, for these dislodged beads act as ball bearing surfaces to increase the tendency of dangerous skids by vehicles, especially under wet traffic conditions;

There is a further disadvantage to spheres which has escaped attention heretofore. Spheres or beads have been believed to be the best reflecting media, particularly when the viewing angle is of the order of 90 removed from the line of light directed at the beads. On the highway, however, the driver never is in a position to view the reflected light at an angle of 90 because the headlights are forward of his position and do not light ice the beads at a point giving the driver aviewing angle even approaching At night, the light source, i.e. the automobile headlights, project a beam at an angle of incidence, evenless than the angle at which the driver observes the reflected scattered light from a traflic paint marking on a road surface.

The present invention is based upon the discovery that reflex reflective qualities can be obtained using in a road marking paint, a combination of glass spheres and glass fragments of a nonspherical surface configuration, constituted by a multiplicity of angularly related planar surfaces. Glass fragments and glass beads combine to attain a high degree of light reflection as hereinafter explained and do not diffuse and dissipate the light to the detriment of visibility as would be expected from the random orientation of reflecting surfaces. This combination of reflex reflective glass material provides excellent visibility and a wider effective viewing angle. It has been found that glass spheres and glass fragments both preferably graded to possess a range of particle sizes, form etfective reflex reflective elements when incorporated in a conventional reflective traflic paint. The reflex reflective elements may be incorporated in the conventional traflic paint in amounts ranging from about 0.5 to 9 lbs. of glass material per gallon of glass-free paint.

When utilizingthe combination of nonspherical planar glass fragments and glass spheres, the reflex reflective action is greatly improved and visibility is maintained for greatly extended periods of time. Intermingling of glass beads and glass fragments provides a longer lasting paint because securely anchored, dimensionally irregular glass fragments extending above the paint'vehicle provide a retarding action to the wearing away of the paint vehicle between glass particles. With a paint vehicle of longer life, the rate at which glass beads become dislodged from the paint layers is markedly less than when the glass beads are used alone.

The nonspherical planar and angular glass fragments of the combination of fragments and spheres by virtue of their dimensional irregularity, and adjacent and overlapping positioning in the paint layer tend to be more securely keyed into the paint layer and are not dislodged as readily as beads by vehicular wear. This resistance to dislodgement is maintained despite the fact that a large portion of the upper surface of the fragment becomes exposed at the time whenthe fragment exhibits elfective reflex reflective action. Beads or spheres on the other hand, have the paint worn from the surface thereof quicker than glass fragments to establish reflex reflective action more quickly after deposition of the paint on a pavement. By the use of the combination of two types of glass particles, the durability of the paint layer is greatly improved because the beads are protected against dislodgement through the presence of closely associated glass fragments solidly keyed in the paint layer and acceptable standards of night visibility are maintained for greatly extended periods' of time.

The invention will now be described in greater detail with reference to the accompanying drawings in which:

FIGURE 1 is a diagrammatic sectional view taken through a reflex reflective highway marking paint constructed in accordance with the invention, said paint having'been freshly painted on a highway;

FIGURE 2 is a fragmentary top plan view of the reflex reflective highway marking paint after the passage of vehicular traflic has abraded the upper surface of the paintfto expose the upper portion of many of the reflex reflective elements incorporated therein.

Referring more particularly to the drawing, the glass particles in FIGURE 1 are generically designated by the numeral 10 and, in accordance with preferred practice of the invention, a plurality of differently sized and shaped particles are present. Thus, the numeral 11 designates some of the larger .sized fragments, the numeral 12 designates some of the smaller size fragments. The numeral 13 designates large .glass spheres or beads and the numeral lddesignates smaller glass spheres.

The glass particles 11, 12, 13 and 14 are, as is apparent from the drawings, and in the embodiment shown, made up of a plurality of non-spherical particles and a minor proportion of glass spheres embedded in a paint vehicle 20 overlaying a cement pavement 15. The various surfaces reflect light in an irregular manner and are angularly interrelated.

While it has generally been assumed that such a combination of spherical and nonspherical particles would cause widespread dispersion of incident light, it has surprisingly been found that improved reflex reflective action is achieved.

The beam of a motorists headlights has a small angle of incidence with regard to the reflective particles. At a motorists viewing angle of 2 to 12, the reflective paint reflects back light fully satisfying rigid highway standards of brilliance. Moreover, adequate visibility is achieved at a range of angularities to permit a centerline to reveal a curve or sweep on the road ahead.

FIGURE 2 clearly shows the manner in which the paint layer 20 is worn away to expose a large portion of the upper surface of the glass fragments 10. As will be evident, a considerable portion of the fragments 10 are exposed and vehicular trafiic cannot further wear away the paint layer 20 until the fragments 10 are dislodged.

The invention'will be more fully understood by ref- 'erence to the following examples which are given without any intention that the invention be limited thereto.

Example I This example illustrates the types of glass particles which are .usable in accordance with the invention. Fragments should be made from a glass composition having a high index of refraction, preferably approximately 1.5 or higher. The glass should 'be transparent, although the degree of transparency may vary within rather wide limits. Preferably, the glass is clear and colorless, and free from milkiness, dark particles and air. Since in use the fragments are exposed to the elements, the glass used should be resistant to the action of water and should be capable of withstanding reflux- K CaO.

The above compositions are crushed to produce fragments suitable for use in accordance with the invention. Thus, glass flake /2 mil in thickness is crushed so that all particles will have at least two reflective surfaces. Fragments are graded to the correct size by separating with vibrating screens of the desired mesh. 7

It has been found that fragments retained by a 270 mesh sieve prossess considerable reflex reflective properties and particles which pass through a 270 mesh sieve can be remelted and recrushed. It is preferred to incorporate a range of differently sized glass particles in a highway marking paint in accordance with the invention. A particularly preferred mixture of nonspherical particles is as follows:

Percent of mixture The mixture above set forth is pictured in a highway marking paint in the drawings where it is incorporated in a layer of paint having a thickness of approximately 5 to 6 mils. A paint including this mixture is adapted to be sprayed with conventional spray'equipment.

It is desired to point out that the invention is not limited to the specific glass compositions A and B of Example 1. Thus, another and a preferred illustrative composition is as follows:

C. Silicate glass-$0 70.6%; Na o, 17.0%, MgO, 0.1%; CaO, 10.6%; A1 0 0.8%.

This glass in flakes approximately /2 mil in thickness is crushed to the desired particle size by hammer-milling. The desired particles are then separated by U.S. standard sieves to recover particles passing through a No. 60 screen and retained on a No. 270 screen.

The mixture of nonspherical particles above set forth is combined with spherical particles of the following description.

The glass bead content may be made up as follows, in

proportion by weight:

7 Percent No. 10 heads, diameter 5.9 mils 20 No. 12 beads, diameter 4.7 mils 55 No. 13 heads, diameter 3.9 mils 25 -It will be understood that the diameters listed .represent an average value only. No. 10 heads, for example, may vary in size from 9.4 to 4.2 mils in diameter although most of the beads will fall Within the limits of 6.6 to 5.2 mils in diameter. The glass utilized in the preparation of such beads may have a refrective index varying from about 1.3 to about 1.6.

The size and density of the beads mustbe taken into account on producing stable paint compositions and long wearing paint films. Large beads or beads of high density are more inclined to settle out from fluid compositions due to their higher ratio of weight to surface. Large beads are also .less firmly bonded in the dried tfil-m, and show a greater tendency to scuff loose under the impact of traffic. On the other hand, extremely fine beads have such enormous surface area in relation to their weight that they unduly extend the paint which then requires excessive dilution and results in lower bonding power. It .is preferred to use for the purposes of this invention, beads in the size range between about 3 and about 10 mils average diameter.

Where transparent beads are employed for their reflectorizing effect as well as their resistance to wear they may be made of glass having any desired reflective index as longas suitable properties of weather resistance and the like are maintained.

Glass particles, useful in this road marking paint, i.e., beads or fragments may be surface treated if desired, either to provide improved adhesion between glass surface and hinder, or to provide a colored or reflective or protective surface, or for any other purpose.

The above described nonspherical and spherical particles may be combined in ratios by weight varying from about 8:1 to about 1:2 and preferably vary from about 3:1 to about 1:1.

It is to be noted that larger particles may-foe used i.e., fragments Which will not pass through a N0. 60 sieve and beads thatare larger than No. 10 heads. However, these larger glass particles are not adapted to a paint intended .to be sprayed usingconventional spray equipment although paints containing these larger particles can be applied in other Ways e.g'., by brushing or by the use of spreaders. Particles of nonspherical configuration and smaller than that retained by a No. 270 US. standard screen are preferably excluded from the paint because these particles thicken the paint and provide little' reflec- In the above varnish base, the phenolic modified pentaerythritol ester of rosin is desirably the product Pentalyn 802A manufactured by Hercules Powder Co. and having the following specification:

Softening point 165 -170 C. Color K. Acid numberu -22.

Viscosity at 25 C.: v V

(a) Linseed oil disper- V Sion poises (mim'mum) Viscosity 600+20 poises (maximum). 40% resin/60%,

oil. (*b) 50% solids C (minimum).

Toluol (G.H.) G (maximum).

The hydrocarbon resin in'the above varnish base is desirably of polymerized unsaturated petroleum monomers consisting essentially of'diene andreactive olefins and having an average molecular weight of 9.0. These unsaturated monomers are polymerized tojform a hard solid having an average molecular weight of 1100. Such a hydrocarbon resin is manufactured by Pennsylvania IndustrialChemical Company as Piccopale. 100 having the following specification:

Softening point 100 C.

Specific gravityat .C.. ..970-.975.

Color... f 13 Gardner-Holdt scale. Acid number; Less than 1. Saponification number Less than 2.

Iodine value (WIJS) 120.

Bromine number 7.3.

Thesvarnish base above specified. is prepared by heating the admixed Pentalyn .802A, Piccopale 100, China-wood oil and'S gallons of linseed oil in a kettle at 560 F. for 45 minutes. The heated mixture is then chilled by the addition of 3.89 gallons. of .linseed. oil and 'allowed to'cool to 350 F. whereupon the naphtha is "added to the mixture. This varnish is employed in a paint composition as fol-lows:

. Lbs. Varnish I 368.5 Titanium dioxide pigment 247.0 Magnesium sili 126.0 Crushed glass 265.0 Glass bea 135.0

Toluene 91.0 VM&P; naphtha 25.0

. 6% cobalt drier .5 24% lead drier 1.5

This paint is compounded by mixing the titanium di-- oxide and the magnesium silicate with 144.6 lbs. of varnish and the mixture is ground on a paint mill. The

driers are then added and the remainder of the varnish and the glass particles mixed thoroughly into themixture. The toluene and naphtha thinners are then added. This 6 paint had a viscosity of Krebs Units and a total solids content of 77%. The weight proportions of this paint are as follows:

Percent Pigment 29,62 Vehicle solids 15.8 Glass 31.78 Thinner' and drier 22.8

The glass particles used were'the crushed glass and glass beads of Example 1.

v The finished paint can be applied'with spraypbrush or roller. Small amounts of naphtha may be used to compensate for individual application technique. If long storage is contemplated, small amounts of antisettlin'g agents, such as calcium linoleate, may be used for suspension.

It has been found that. the crushed glass fragments,

.perhaps due to their geometrical angularity, are more satisfactorily maintained in satisfactory suspsension than spherical beads. This is particularly true for the heavier particles, e.g., those retained by a 60 mesh screen and this is of particular value in' paints adapted for brush,

roller or spreader application as contrasted with spray application.

' Example 3 The following illustrates a paint composition employ- .ing as the vehicle a phthalic alkyd containing 30% phthalic anhydride having a soya' modification of 55%, the alkyd being prepared using glycerin as the polyhydric alcohol and having the following characteristics in a 60% petroleum spirits solution:

Solids 60%. Viscosity Zl-Z3 Gardner-Holdt. Color (Hellige) l-3.

Acid number-" 4-6.

Poundsper gallon 7.8. -Phthalic anhydridenn 30% (on resin solids). Oil acid 'content 50% (on resin solids). Type of oil Soya.

Ari alkyd of the above composition and having the characteristics stated is sold by General Electric Company under the trademark Glyptal" 2475.

1 Paint composition: 7 Lbs. Titanium dioxide 2Z5 Phthalic alkyd (50% solids); 400 Calcium carbonate Crushed glass 26S Glass beads VM&P naphtha 116 Cobalt drier .5 Lead drier 1.5

This paint was prepared by adding the titanium dioxide and calcium carbonate to 300 lbs. of the phthalic alkyd vehicle. This mixture was ground on a paint mill and the remainder ofthe vehicle added. The glass particles (as specified in Example 1) were then stirred in thoroughly and the naphtha and driers added.

Example 3 is modified by using as the vehicle for the paint, a 30% phthalicpentaerythritol alkyd modified with 54% of an oil consisting of equal parts by volume of linseed oil and soya oil having the following characteristics: V

Solids 50%.

50% VM&P naphtha. 50% Mineral spirits. Acid number 10.2. Color 7 (Gardner Holdt). Pounds per gallon 7.50. Viscosity V-W (Gardner Holdt).

This-alkyd is sold by American-Marietta Company under N0. SV-141B7.

' Example-4 The reflectorized paint may also be of the emulstion type as is illustrated by the following:

IIElgment grind: Lbs. Water V 20.0 Tetrasodium pyrophosphate decahydrate,

aqueous solution 10.0 Emulphor .EI=719 dispersing and wetting agent 2.0 Polyglyeol P-1200 polypropylene glycol 2.0 Carbltol-diethylene glycol monoethyl ether 25.0 Dibutyl phtlralate 18.0 ASP-400 clay 75.0 Titanium dioxide 100.0

Reduction:

Water 130.0 Methocel 4000 methyl cellulose, 2.0% aqueous solution 260.0 Du Pont "Elvacet 81900 polyvinyl acetate emulsion 320.0 Crushed glass (as specified in Example 1) 300.0

Emulphor Ell-.719 is a polyoxyethylated vegetable oil which is used to promote wetting and stabilize the emulsion. p

The Polyglycol P 1200 is -a polypropylene glycol with an approximate molecular weight of 1200. It is formed by the addition of propylene oxide to propylene glycol. P '1200acts as an anti-foaming agent for the emulsion.

Example 5 Resin solution types, either synthetic or natural, can be used, giving a quick drying paint resistant to wear. Typical example:

Lbs. Titanium dioxide 200.0 Resin solution (50% manila resin-alcohol) 400.0 Magnesium silicate 125.0 Crushed glass 200.0 Glass beads 200.0 Ethyl alcohol 116.0

When synthetic resins are used, the thinner is simply varied to give optimum results. Thesereflectorized center line paints dry quickly by evaporation although in general they are not as tough as resinous paints.

Example 6 The following is a specific illustration of a graded mixture of crushed glass fragments containing fragments which are retained by a #60 mesh screen. These'larger particles prevent sprayability 'in ordinary spray equipment because they tend to clog conventional spray equipment, butthey maybe used advantageously in producing paints for roller application. In such paints, up to about 50% by weight of particles which pass through a #40 mesh screen but are retained by a 60 mesh screen may be used. Particles retained by a #40 mesh screen but not by 'a mesh screen may also be used in an amount not exceeding about 20% by weight. The use of still larger particles is not recommended, although up to 5% by weight of slightly larger particles can be tolerated.

These larger particles, --when incorporated in a highway marker paint formulation, provide enhanced brilliance of night visibility and are ofagreat valuexin speed-' ing the initiation of the reflex reflective action upon vehicular abrasion of the traffic'marker.

Preferred graded mixtures 'for roller application contain from 5-'2S% of particles which pass through a #40 mesh screen'but whichare retained by a #60 mesh screen and IO-30% of particles which pass through .a #60 mesh screen and not a mesh screen. Thus, a particularly preferred mixture of nonspherical glass fragments in cluding a proportion of heavier glass particles, e.g., those retained by a #60 meshiscreen, is as'follows:

Percent of mixture Sieve size: passing through US. Standard No. 40 sieve 'U.S. Standard No. 60 sieve 90 US. Standard No. 80 sieve 75 US. Standard No. sieve. 15-25 US. Standard No. 230 sieve 0--10 US. Standard No. 270 sieve 0 The glass used in the above set forth mixture may .be of any of the glass compositions A, B .and'C which are more fully set forth in Example 1. This mixture may be incorporated in any of the reflective paint compositions set forth in Examples 2, 3, 4 and 5 together with the specified glass beads to provide an effective highway marking pain-t having great durability and enhanced brilliance of night visibility in comparison with the use of the mixture of differently sized glass fragments set forth in Example 1.

It is desired to emphasize that the presence of a substantial proportion of glass fragments or particles which are retained by a #60 mesh screen and beads larger than #8 causes the highway marking paint containing these glass particles to clog conventional spray equipment. Hence, and as a practical matter, these latter highway marking paints, including large sized incorporated glass particles, are not amenable to spray application. However, these paints may be applied efliciently to highways in many manners other than spraying as, for example, roller coating, in which instance the presence of the larger size particles or fragments does not prevent effective application of the paint incorporating the glass fragments.

Under abrasion, due to wear by vehicular traffic, the surface of the above exemplary paints wears away to expose the glass particles for their reflex reflective function.

FIGURESI and 2 pictorially distingu'ishbetween fragments and beads by showing the fragments as having flat angular surfaces and irregular nonspherical shapes whereas the glass beads are-shown as spheres. The presence of the combination of fragments and spheres is of paramount importance, Light is reflected from the surface or surfaces of fragments and spheres in directions dependent upon the angle of incidence of the light. Light reflected in a direction other than toward the vehicle driver when using the combinationofspheres and vfragments is not entirely diffused and lost. Reflection by random oriented. faces of .glass fragments of at least some of the light reflected from beads in a direction other than toward the vehicle driver or reflection by spheres of light directed-thereto by reflection from fragments, is at least partially converted' to reflected light thus maintaining adequate visibility and brilliance under widely varying and rapidly changing conditions of lighting.

We claim:

1. A reflective highway marking paint comprising a paint vehicle containing between about 0.5 lb. and about 8 lbs. of a suspended mixture of glass particles per gallon of glass-free paint, said glass particles being amixture .of transparent glass beads having an average diameter of the order of about 3 to about 10 mils'and glass'fragments being of a size to be retained by a US. Standard No. 270 .mesh screen and being constituted by a'plurality of angularly intersecting substantially planar light reflecting faces, the ratio of said glass beads :to glass fragments being in the-range between 2:1 and 1:8, and said fragments being present insuflicient concentration such that when applied to a highway as a marking paint the fragments provide with the binder a keying action whereby dislodgements of fragments and spheres is resisted.

2. A reflective highway marking paint comprising a drying oil-base varnish vehicle containing between about 0.5 lb. and about 8 lbs. of a suspended mixture of glass particles per gallon of glass-free paint, said glass particles being a mixture of transparent glass beads having an average diameter of the order of about 3 to about mils and glass fragments being of a size to be retained by a US. Standard No. 270 mesh screen and being constituted by a plurality of angularly intersecting substantially planar light reflecting faces the ratio of said glass beads to glass fragments being in the range between 2:1 and 1:8, and said fragments being present in suflicient concentration such that when applied to a highway as a marking paint the fragments provide with the binder a keying action whereby dislodgements of fragments and spheres is resisted.

3. A reflective highway marking paint comprising a paint vehicle containing between about 0.5 lb. and about 8 lbs. of a suspended mixture of glass particles per gallon of glass-free paint, said glass particles being a mixture of transparent glass beads having an average diameter of the order of about 3 to about 10 mils and glass fragments of a particle size passing through a US. Standard No. 270 mesh screen and being constituted by a plurality of angularly intersecting planar fight reflecting faces, the ratio of said glass beads to glass fragments being in the range between 1:1 and 1:3, and said fragments being present in sufiicient concentration such that when applied to a highway as a marking paint the fragments provide with the binder a keying action whereby dislodgements of fragments and spheres is resisted.

4. A paint as claimed in claim 2 wherein said varnish vehicle is a vegetable oil modified alkyd resin of phthalic anhydride and glycerin which is dispersed in an organic solvent.

5. A paint as claimed in claim 2 wherein said glass fragments have a refractive index of at least 1.5.

6. A reflective highway marking paint comprising a paint vehicle containing a reflective pigment dispersed therein and between about 0.5 lb. and about 8 lbs. of a suspended admixture of glass particles per gallon of glassfree paint, said glass particles being a mixture of transparent glass beads having an average diameter of the order of about 3 to about 10 mils and light reflecting glass fragments of a size to pass through a US. Standard No. 60 mesh screen and to be retained on a US. Standard No. 270 mesh screen, the ratio of said glass beads to glass fragments being in the range between about 2:1 and 1:8,

and said fragments being present in suflicient concentration such that when applied to a highway as a marking paint the fragments provide with the binder a keying action whereby dislodgements of fragments and spheres is resisted.

7. A paint as claimed in claim 6 wherein said reflective pigment includes titanium dioxide.

8. A reflective highway marking paint comprising a paint vehicle containing between 0.5 lb. and about 8 lbs. of a suspended admixture of glass particles per gallon of glass-free paint, said glass particles being a mixture of transparent glass beads having an average diameter of the order of about 3 to about 10 mils and glass fragments sufficiently large to be retained by a US. Standard No. 270 mesh screen and being constituted by a plurality of angularly intersecting substantially planar light reflecting faces, said glass fragments comprising up to about 50% by weight fragments retained by a US. Standard No. mesh screen and passing through a US. Standard No. 40 mesh screen, and said fragments being present in suflicient concentration such that when applied to a highway as a marking paint the fragments provide with the binder a keying action whereby dislodgements of fragments and spheres is resisted.

9. A reflective highway marking paint comprising a paint vehicle containing between about 0.5 lb. and about 8 lbs. of a suspended mixture of glass particles per gallon of glass-free paint, said glass particles being a mixture of transparent glass beads having an average diameter of the order of about 3 to about 10 mils and glass fragments being of a size to be retained by a US. Standard No. 270 mesh screen and being constituted by a plurality of angularly intersecting substantially planar light reflecting faces the ratio of said glass beads to glass fragments being in the range between 2:1 and 1:8, the glass particle loaded paint being adapted to be sprayed on highway surfaces subject to vehicular traflic to provide nighttime visibility to motorists, and said fragments being present in suflicient concentration such that when applied to a highway as a marking paint the fragments provide with the binder a keying action whereby dislodgements of fragments and spheres is resisted.

References Cited in the file of this patent UNITED STATES PATENTS 2,354,108 Heltzer et a1. July 18, 1944 2,574,971 Heltzer Nov. 13, 1951 2,574,972 Hill Nov. 13, 1951 2,824,502 Rockwell et a1. Feb. 25, 1958 2,865,266 Wynn Dec. 23, 1958 UNITED STATES PATENT. OFFICE CERTIFICATE OF CORRECTION Patent N00 3,005fl90 October 24 196 James F Wynn et all,

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below Column l line 21 after "conventional" insert refler column 3 line "(l for 'prossess" read possess column l line ll for "refrective"- read refraction column 7 line 2 for emulstion" read emulsion columu l0 line 4'7 for the patent number "2 354 108" read 2 354 018 Signed and sealed this 24th day of April 1962.

(SEAL) Attest:

ESTON' Ga JOHNSON DAVID L. LADD Attesting Officer Commissioner of Pate.

Claims (2)

1. 2. A REFLECTIVE HIGHWAY MARKING PAINT COMPRISING A DRYING OIL-BASE VARNISH VEHICLE CONTAINING BETWEEN ABOUT 0.5 LB. AND ABOUT 8 LBS. OF A SUSPENDED MIXTURE OF GLASS PARTICLES PER GALLON OF GLASS-FREE PAINT, SAID GLASS PARTICLES BEING A MIXTURE OF TRANSPARENT GLASS BEADS HAVING AN AVERAGE DIAMETER OF THE ORDER OF ABOUT 3 TO ABOUT 10 MILS AND GLASS FRAGMENTS BEING OF A SIZE TO BE RETAINED BY A U.S. STANDARD NO. 270 MESH SCREEN AND BEING CONSTITUTED BY A PLURALITY OF ANGULARLY INTERSECTING SUBSTANTIALLY PLANAR LIGHT REFLECTING FACES THE RATIO OF SAID GLASS BEADS TO GLASS FRAGMENTS BEING IN THE RANGE BETWEEN 2:1 AND 1:8, AND SAID FRAGMENTS BEING PRESENT IN SUFFICIENT CONCENTRATION SUCH THAT WHEN APPLIED TO A HIGHWAY AS A MARKING PAINT THE FRAGMENTS PROVIDE WITH THE BINDER A KEYING ACTION WHEREBY DISLODGEMENTS OF FRAGMENTS AND SPHERES IS RESISTED.
2. 4. A PAINT AS CLAIMED IN CLAIM 2 WHEREIN SAID VARNISH VEHICLE IS A VEGETABLE OIL MODIFIED ALKYD RESIN OF PHTHALIC ANHYDRIDE AND GLYCERIN WHICH IS DISPERSED IN AN ORGANIC SOLVENT.

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